36 



OUTLINES OF NATURAL HISTORY. 



composed of seven distinct joints or pieces. They are 

 fixed at their bases to a strong horny plate which covers 

 the chest in front. 



Pig. IS-— A, The male of the common House Spider (Tegenaria civilh), con- 

 siderably magnified ; c Front portion of the body, consisting of the amal- 

 gamated head and thorax ; p Feelers attached to the jaws ; a Abdomen. 

 B, Front portion of the head of the same, showing the eight eyes (/), and 

 the poison-jaws (n). C, Under side of the head and trunk, showing the 

 true jaws (m), the lower lip (I), and the horny plate to which the legs are 

 attached. D, Diagram of one of the air-chambers or breathing-organs. 

 (Figs. A, B, and C are after Blackwall.) 



Upon the front of the head are situated eight simple 

 eyes (fig. 15, B, /), arranged in two lines, the pairs which 

 occupy the ends of the line being placed on small tuber- 

 cles. On the under surface of the head is situated the 

 opening of the mouth, and in front of this are two organs, 



